Tuesday, May 5, 2009

Dirty Snow

I spent the other day checking out the early May snowpack on Red Mountain Pass here in the San Juan Mountains...some one had to do it! Our winter produced an above average snowpack (just barely) which bodes well for the summer wildflowers and low elevation irrigation, but it is melting rapidly. This winter also produced three strong wind events that blew red dust in from Utah. The higher elevations were covered in red snow while the lower elevations saw muddy rain. The dust on the surface of the snow impacts the albedo and less solar energy is reflected back into the atmosphere. In addition, the desert dust that is mixed throughout the snowpack has a different specific heat than the snow. As the spring temperatures warm, these dirt and dust particles heat up faster and in turn melt the snow faster than historical records would suggest. Snowpack that once would last into July is now melting out in June. Rivers which should run high into the early summer peak out in May.

The last image shows the current state of the Gunnison basin snowpack. The smooth line represents the 30 year average. Look at the slope of the last few years of snow melt. I think there is a message here.